Severe air pollution shrouded the horizon as the pollution season escalated in Bangkok, Thailand, this week.

Footage shows the grey hazardous smog containing deadly PM2.5 particles hanging over homes on January 9. Unsafe levels of air pollution have also been reported to blanket dozens of Thai provinces.

Air pollution levels in most areas across Thailand were reported to be unhealthy.

The Geo-Informatics and Space Technology Development Agency (Gistda) reported on January 8 at 8 am that 39 provinces had PM 2.5 fine dust levels in the 'red' hazardous range.

The Pollution Control Department stated that stagnant air had caused smog to accumulate in Greater Bangkok, the Lower North, and the Northeast. The department said they expected the situation to improve by January 11.

Dangerous levels of deadly PM 2.5 particles - which cause cancer and other debilitating illnesses - are recorded every year in Thailand between December and April when farmers across Southeast Asia burn waste crops to clear their land.

The rudimentary method, known as 'slash and burn', is quicker and cheaper than modern machinery, leaving relatively poor landowners unwilling to heed environmental and health concerns over economic necessity.

Despite paying lip service for several years, politicians have failed to stop individuals from burning their land due to it being cheaper and easier than modern farming methods.

In March 2023, the Public Health Ministry of Thailand reported that around 1.3 million people in the country had been unwell due to the rising levels of air pollution. Officials said 200,000 residents were hospitalised in a single week.

Researchers from Peking University in Beijing, China, found that exposure to PM 2.5 air pollution is associated with an increased risk of lung cancer.

In December, Dr Krittai Thanasombatkul from Chiang Mai - one of the world's worst cities for air pollution - died of lung cancer. He had previously blamed PM 2.5 microdust particles for his condition.

The New York State Department of Health says PM 2.5 also increases the risk of heart disease, asthma, and low birth weight.

Medics from South Korea published research in the National Institute of Health in the United States that said the pollutant increases the risk of stroke, ischemic heart disease, chronic obstructive pulmonary disease (COPD), lung cancer, and other illnesses such as immune deficiency and even obesity.